Compressor.



No. 792,790. PATBNTED JUNE 20,1905.

W. PRELLWITZ. COMPRESSOR. APPLICATION FILED JUNE 2, 1904.

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.UNITED STATES Pateiitec'l June 20, 41905 PATENT trice,

IVILLIAM PRELLWITZ, OR EASTON, PENNSYLVANIA, ASSIGNOR TO THE INGERSOLL-SERGEAN'I DRILL COMPANY, OF NEV YORK, N, Y., A CORPORATION OF VEST VIRGINIA.

COMPRESSOR.

SPECIFICATION forming partof Letters Patent No'. 792,790, dated June 20, 1905.-

Appl'eatien filed julle 2,1904. Sllitl N0. 210,827.

single-acting compressor, whereby a coml pressor ot' this type is given much greater eiiiciency than has heretofore been possible. n

A practical embodiment of this invention is represented in the accompanying drawing, which shows the compressor and its intercooler in longitudinal central section.

The low-pressure cylinder is denoted by l. its piston by 2, and its outer cylinder-head by 3. The high-pressure cylinder is denoted by 4, its piston by 5, and its outer cylinderhead by 6. The low and high pressure pistons 2 and 5 are connected to move simultaneously in the same direction by a piston-rod 7, and the low-pressure piston 2 is provided with an operating piston-rod 8, which passes through suitable packed bearings in the lowpressure outer c,\f'linderhead 3.

Communication between the chamber 9 at the back of the piston 2 and the compressionchamber 10 at the front of the piston is controlled by an annular valve Il, which is arranged to control an annular port l2 in the said piston. Y

Communication is opened and closed'between the chamber 13 at the back of the piston 5 and the high pressure compressionchamber I4 at the front ot' the piston by an annular valve I5, which is arranged to open and close an annular port 16 in saidpiston.

An intermediate head I7 is located between the low and high pressure cylinders, which head forms the common inner cylinder-head of the low and high pressure cylinders. The piston-rod 7 which connects the two pistons is fitted to reciprocate in suitable packed bearings in the said intermediate head.

The low-pressure cylinder is supported upon a suitable base 18. and the high-pressure cylinder is supported by an upright I9, mounted on a floor or other suitable support 20. This upright I9'is hollow and forms the Huid-inlet 21. This Huid-inlet 21 communicates with a duct 22, located along the wall of the highvpressure cylinder, which duct opens into the supply-chamber 9 in the lowpressure cylinder,

The i'ntercooler is denoted by 23. An outlet-port` 24 'for the low-pressure compression- 4chamber l() is controlled by a puppet-valve 25, and a duct 26 leads therefrom to the inlet end 27 of the intercooler. A duct 28 leads `from the outlet end 29 of the intercooler to the chamber 13 in the high-pressure cylinder back ot' the piston. The (ilischarge-port ot' the high-lmessure chamber 14 in Front of the piston 5 is denoted by 30, and it is controlled by a puppet-valve 31.

To gain access to the packed bearing `for the piston-rod 7 in the intermediate head 17, I provide a manhole-cover 32 upon each side of the said packed bearing, one only of said Ymanhole-covers being shown herein.

In operation as the low-pressure piston 2 is moved inwardly the valve 1I therein is opened, permitting` the fluid to pass into the chamber 10. As the piston is moved `forward the tluid is compressed and forced past the puppetvalve 25 through the intercooler and into the chamber 13 back ot' the high-pressure piston and from thence past the open valve 15 the-rein into the chamber 14. movement ot' the low-pressure piston 2 and corresponding outward movement of the highpressure piston 5 will discharge the Huid `from the chamber 14 by the puppet-valve 31 and at the same time draw in a new supply oli' Huid into the chamber 10 in front of the low-pressure piston. v

It has heretofore been common to admit atmospheric pressure back ot' the low and high pressure pistons, the fluid vfrom the intercooler The next inwardv being led to the front end of the high-prespressure cylinders, valved pistons therefor,

intermediate head 17 I am enabled to keep sure cylinder and caused to enter the latter through a puppet inlet-valve. By using the the intercooler-pressu re back ofthe high-pressure piston, thus allowing the proportion of the two cylinders to be the same as V'if they were made double-acting and keep the maximum and mean strains the same at each end of the stroke. Also any leakage of fluid past the high-pressure piston during compression will pass to the chamber having fluid raised above atmospheric pressure rather than to the atmosphere. Furthermore, in the common form as the piston in the low-pressure cylinder was compressing the fluid, there was cooler-pressure on the inlet side of the highpressure piston, this pressure helping the lowpressure cylinder to do its work. On the return stroke, the high-pressure piston compressed the fluid, but had no cooler-pressure back of it to help it. To equal the mean effective pressure, it was necessary to compress to a higher pressure in the low-pressure cylinder than would be necessary with a compound double-acting machine. By the use of the intermediate head, as herein described, the conditions are the same whether the machine is compound, double-acting, or singleacting.

What I claim as my invention is- 1. In a compressor, separated low and high inlets at the approximate ends ofthe cylinders and outlets at their other ends, and means for J leading the compressed fluid from the outlet of the low-pressure cylinder to the inlet of the high-pressure cylinder.

2. In a compressor, separated low and high pressure cylinders, valved pistons therefor, inlets at the approximate ends ofthe cylinders and outlets at the other ends of the cylinders, an intercooler, and means for leading the compressed fluid from the outlet of the low-pressure cylinder through the intercooler to the inlet of the high-pressure cylinder.

3. In a compressor, low and high pressure cylinders, valved pistons therefor, a common head separating the two cylinders, inlets at the adjacent ends of the cylinders, outlets at the other ends of the cylinders, and means for leading the compressed fluid from the outlet of the low-pressure cylinder to the inletl of the high-pressu re cylinder. y

4. In a compressor, separated low and lhigh pressure cylinders, valved pistons therefor, open inlets at the approximate ends of the cylinders, valved 'outlets at the other ends of theJ` cylinders, and means for leading the compressed fluid from the valved outlet of the low-pressure cylinder to the open inlet of the high-pressure cylinder.

In testimony that I claim the foregoing as my invention I have signed my name, in presience of two witnesses, this 31st day of May, 1904.

WILLIAM PRELLWITZ. Witnesses:

WARD RAYMOND, RUSSELL WILHELM. 

